Probing the cosmic distance-duality relation with the Sunyaev-Zel'dovich effect, X-ray observations and supernovae Ia
Probing the cosmic distance-duality relation with the Sunyaev-Zel'dovich effect, X-ray observations and supernovae Ia
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DOI：
10.1051/0004-6361/201118343
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发表时间：
2011-04
影响因子：
6.5
通讯作者：
R. Holanda;J. Lima;M. B. Ribeiro
中科院分区：
文献类型：
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作者：
R. Holanda;J. Lima;M. B. Ribeiro
语境。到星系团的角直径距离可以通过测量Sunyaev-Zel'dovich效应和X射线表面亮度并结合距离对偶关系DL(z)(1 + z) 2 /DA(z) = 1的有效性来确定，其中DL(z)和DA(z)分别是光度和角直径距离。这种组合使我们能够探测星系团物理，甚至测试距离对偶关系本身的有效性。目标。我们基于两种不同但互补的方法探索这些可能性。首先，为了约束可能的星系团形态，在ΛCDM框架（WMAP7）中假设距离对偶关系（DD关系）的有效性。其次，通过采用与宇宙学模型无关的测试，我们直接用两个超新星 Ia (SNe Ia) 子样本（精心选择以与星团位置一致）来面对星系团的角直径。还讨论了前面分析中不同 SNe Ia 光曲线拟合器的影响。方法。我们假设 η 是由两个不同关系参数化的红移函数： η(z) = 1 + η0z ,a nd η(z) = 1 + η0z/(1 + z)，其中 η0 是一个常量参数，量化可能偏离 DD 关系严格有效性的情况。为了确定 η0 的概率密度函数 (PDF)，我们通过假设椭圆和球形等温 β 模型以及球形非等温 β 模型，考虑了最近由两个不同组研究的星系团的角直径距离。仅当 η0 PDF 的最大值以 η0 = 0 为中心时，DD 关系才会严格有效。 结果。对于这两种方法，我们发现椭圆 β 模型与距离对偶关系一致，而非等温球形描述在最好的情况下只是勉强兼容。我们发现双光曲线拟合器（SALT2 和 MLCS2K2）存在统计上显着的冲突，并且涉及不同方法的联合分析表明簇被赋予了先前假设的椭圆几何形状。结论。这里提出的统计分析提供了新的证据，表明簇的真实几何形状是椭圆形的。原则上，值得注意的是，诸如星系团几何形状之类的局部属性可能会受到诸如宇宙距离对偶关系所提供的全局论证的约束。
Context. The angular diameter distances toward galaxy clusters can be determined with measurements of Sunyaev-Zel’dovich effect and X-ray surface brightness combined with the validity of the distance-duality relation, DL(z)(1 + z) 2 /DA(z) = 1, where DL(z )a nd DA(z) are, respectively, the luminosity and angular diameter distances. This combination enables us to probe galaxy cluster physics or even to test the validity of the distance-duality relation itself. Aims. We explore these possibilities based on two different, but complementary approaches. Firstly, in order to constrain the possible galaxy cluster morphologies, the validity of the distance-duality relation (DD relation) is assumed in the ΛCDM framework (WMAP7). Secondly, by adopting a cosmological-model-independent test, we directly confront the angular diameters from galaxy clusters with two supernovae Ia (SNe Ia) subsamples (carefully chosen to coincide with the cluster positions). The influence of the different SNe Ia light-curve fitters in the previous analysis are also discussed. Methods. We assumed that η is a function of the redshift parametrized by two different relations: η(z) = 1 + η0z ,a ndη(z) = 1 + η0z/(1 + z), where η0 is a constant parameter quantifying the possible departure from the strict validity of the DD relation. In order to determine the probability density function (PDF) of η0, we considered the angular diameter distances from galaxy clusters recently studied by two different groups by assuming elliptical and spherical isothermal β models and spherical non-isothermal β model. The strict validity of the DD relation will occur only if the maximum value of η0 PDF is centered on η0 = 0. Results. For both approaches we find that the elliptical β model agrees with the distance-duality relation, whereas the non-isothermal spherical description is, in the best scenario, only marginally compatible. We find that the two-light curve fitters (SALT2 and MLCS2K2) present a statistically significant conflict, and a joint analysis involving the different approaches suggests that clusters are endowed with an elliptical geometry as previously assumed. Conclusions. The statistical analysis presented here provides new evidence that the true geometry of clusters is elliptical. In principle, it is remarkable that a local property such as the geometry of galaxy clusters might be constrained by a global argument like the one provided by the cosmological distance-duality relation.